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After 13 years in orbit, Cassini data still show conflicting interpretations for the age of Saturn’s rings.Scientists like to hope that new spacecraft data will confirm their beliefs. Before Cassini arrived at Saturn in 2004, ring scientists fretted over Voyager data that suggested that the rings were young (much younger than Saturn, according to conventional models). Would Cassini help lengthen the age? Here are some of the latest papers and articles:Ancient Young Rings: Saturn Still Puzzles Astronomers (Space.com). Astrophysicist Paul Sutter reviews the history of ring observations, finally getting to “The contradiction of Saturn” – i.e., evidences that go in opposite directions about the age of the rings. The purity of the rings indicates they must be young. But to keep them old, Sutter only can offer the idea that the best time for Saturn to have formed rings was when the planet formed: “Ergo, these are old rings.” Observation should trump imagination.Surface roughness of Saturn’s rings and ring particles inferred from thermal phase curves (Icarus). While not addressing ring age specifically, this paper reminds readers that the rings are dynamic systems, subject to clumping, erosion and roughening. Could that go on for 4.5 billion years?Saturn’s surprising rings: The fascinating mysteries Cassini has solved (Fox News Science). Reminding readers of the age conundrum after Voyager, this article reminds readers that the ring particles constantly jostle one another, clump up and disperse. The F-ring, especially, is frequently subject to bombardments by Prometheus, which “pokes” the thin F-ring and sends out streamers of particles. Also, the rings are far brighter than they should be if old. And if they are only 100 million Darwin Years old, as data suggests, Cassini has shown that they could not have been produced by a single event, such as an asteroid breakup.Direct detection of gaps in Saturn’s A ring (Icarus). Nearly half a million gaps have been detected in the A-ring of Saturn by the ultraviolet spectrometer. While not addressing ring age, this find shows that the structure and dynamism of these gaps, caused by self-gravity wakes according to models, adds to questions how the structures could persist for billions of years.Saturn’s rings and associated ring plasma cavity: Evidence for slow ring erosion (Icarus). Based on just four hours of data in 2004, the Radio and Plasma Wave Spectrometer (RPWS) team has extended the ages of the rings: “we conclude that A-, B-, and C- ring lifetimes in the space environment can extend back to the formative periods of planet. Losses via the space environment will not limit ring lifetimes to the short 10′s of Myrs time scales.” But this is based on only one factor, the erosion rate by micrometeoroids, which they determined in that small window of time was slower than previously thought. They also admit that the erosion rate may be episodic, and they say that much more data is needed to determine the rings’ age. Their conclusion includes other caveats:Admittedly, the Cassini RPWS is not sensitive to submicron and nano-sized grain impacts, and the loss of these particles cannot be determined. Also, Cassini passed over the northern portion of the rings, and the loss via the instability is expected to be largest in the southern hemisphere. However, there should still be a population of unstable ions, appearing as a ‘fountain’ of ions from the B/C ring boundary and C ring, on the northern side as well (see Fig. 2b of Tseng et al., 2013). Evidence for such an ion fountain is not observed in the corresponding electron density as detected by the RPWS plasma waves.We conclude that the lack of the ion fountain and lack of substantial loss along the B-C ring boundary suggests some other inter-ring process, like local grain cohesion and/or electrostatics, is maintaining stability, offsetting the forces that create the instability and loss.A single measurement that could possibly extend the lifetime of the rings does not overthrow other measurements that constrain the age. For instance, collisional spreading should undo much of the fine structure of the rings, sending some particles outward and others into the planet as particles bump into each other. The “propeller” structures in the rings indicate the wearing down of large ring particles that should no longer exist after billions of years. And over such a long time period, impacts by large bodies should have removed ring particles and discolored the ones that remain. Sunlight pressure, sputtering and other processes can additionally erode the rings.As Cassini completes its final high dives through the D-ring gap, data are being collected that should surpass that gathered by the RPWS team in 2004. It will be interesting to see papers on the new high-resolution images and data taken during this final phase of the mission that ends on September 15.(Visited 372 times, 1 visits today)FacebookTwitterPinterestSave分享0
Golden PumpkinIt took a public protest at Kochi Doordarshan Kendra for officials to become worried about their inability to telecast the ongoing football World Cup. Having lost out in the bidding to Abdul Rehman Bukhatir’s fledgling satellite channel, TEN Sports (which reportedly paid Rs 20 crore for the event), DD,Golden PumpkinIt took a public protest at Kochi Doordarshan Kendra for officials to become worried about their inability to telecast the ongoing football World Cup.Having lost out in the bidding to Abdul Rehman Bukhatir’s fledgling satellite channel, TEN Sports (which reportedly paid Rs 20 crore for the event), DD showed little urgency in damage control, perhaps convinced that football was a passion indulged in only by beer-drinking louts and yobs with painted faces.Not true, says DD Director-General S.Y. Quraishi. “We don’t have Bukhatir’s deep pockets. We did bid for the rights but couldn’t afford them.”They tried, he says, but TEN Sports continued to play “hide and seek” with them until B4U finally offered them the terrestrial rights-a peculiar move given B4U is a satellite channel. DD has now signed a deal with B4U, which will pay Rs 50,000 per half-hour for daily highlights of 60 matches between 11 p.m. and 12 p.m. B4U will market the event and DD will save face, somewhat.DD will show the opening and closing ceremonies in full as well as the semi-finals on National Network. But don’t pop the bubbly yet: even these matches will not be shown live.”I’m not happy,” says Quraishi. “In 1998, I sat up to watch all the matches on DD till 3 a.m. every day.” Fancy that.
Jaipur: Rajasthan Assembly on Friday passed a Bill to make ex-ministers shell out Rs 10,000 a day if they continue to occupy government bungalows beyond two months after the end of their terms. The Rajasthan Ministers’ Salaries (Amendment) Bill, 2019, introduced by the Ashok Gehlot-led Congress government on July 22 was passed by a voice vote, amid opposition from the BJP. Ex-ministers now pay Rs 5,000 a month after the two-month period. When the Bill becomes law, they will pay Rs 3 lakh if they overstay beyond this. The Bill also includes provisions for forcible vacation of government accommodation. Parliamentary Affairs minister Shanti Dhariwal said the Bill was brought to ensure that new ministers get official residences in time. It is seen that ex-ministers do not vacate the official residences allotted to them even after the prescribed period is over. This causes difficulty in the allotment of suitable residences to the newly appointed ministers, a statement on the objectives of the Bill said. The Congress came to power in the state last December, replacing the Vasundhara Raje-led Bharatiya Janata Party. During the debate, Leader of Opposition Gulab Chand Kataria said former ministers should vacate their official residences but the government should reconsider the time being allowed to do so. He said the penalty of Rs 10,000 per day was too high. Deputy Leader of Opposition Rajendra Rathore claimed there was a hidden agenda.
Islamabad: Pakistan Prime Minister Imran Khan faces an embarrassing situation as an electricity company has threatened to disconnect the power supply to his sprawling office in Islamabad if the bills worth lakhs of rupees were not paid by his cash-strapped government. The Islamabad Electric Supply Company (IESCO) on Wednesday issued a notice to the PM Secretariat that it will cut off the power supply if the bills were not cleared. The IESCO said that the PM Office owed Rs 41 lakhs. The PM Secretariat did not pay Rs 35 lakh of the previous month also, it added. The PM Office failed to respond to several reminders, the company said. Also Read – Saudi Crown Prince ‘snubbed’ Pak PM, recalled jet from USUnder the law, the company can disconnect power supply by issuing a warning if the bills of the two consecutive months are not paid. Due to the non-payment of bills, the company cannot pay to the private power producers which affects power generation. said the power supply in Pakistan has improved this year after many worst years in the past. Officials say that one of the reasons for low productivity was the unpaid bills by the government departments. Also Read – Record number of 35 candidates in fray for SL Presidential pollsAccording to estimates, 22,000-24,000 megawatt electricity is needed in Pakistan. This demand increases up to 5 per cent each year. The Pakistan government claimed to produce 24,000MW electricity last year. But even the National Transmission and Despatch Company (NTDC), which is an institution of the government, does not confirm it. The difference between demand and supply which was 5,000MW in 2013, has reached up to the level of 6,000MW in 2018, according to reports. In June, Minister for Power Omar Ayub said that power generation improved due to better management. He said there was USD 80 billion investment opportunity in power generation and distribution sector. Pakistan is facing “significant economic challenges” due to a weak and unbalanced growth and that its economy is at a critical juncture where it needs an ambitious and bold set of reforms, according to the IMF, which last month approved a USD 6 billion bailout package to the country. Pakistan has also received billions in financial aid packages from friendly countries like China, Saudi Arabia and the UAE during the current fiscal year.
Cambridge Analytica: firm at the heart of Facebook scandal A State Department official told AFP on Monday the agency’s Global Engagement Center has a contract with Strategic Communications Laboratories (SCL) Group, the parent company of under-fire Cambridge Analytica.The agency has no business with CA, but SCL is closely tied to its offshoot and Facebook announced last week that it was suspending both, under the title “SCL/Cambridge Analytica,” from its platform.A public record of the contract on a US government site, spotted by the Defense One news website, lists its value as $496,232 and states it was awarded to the “SCL Group Ltd of London” on February 17, 2017.The State Department official said the contract was to provide “research and analytical support in connection with our mission to counter terrorist propaganda and disinformation overseas.”SCL, in particular SCL Defence, has done work for other parts of the US government in the past and is a major company in the field of research and analytics,” she said, speaking on condition of anonymity.The Global Engagement Center was set up under former US president Barack Obama to analyze and push back against online propaganda and recruitment by armed extremist groups such as the Islamic State.Since Donald Trump came to office, Congress has assigned $120 million to the center to counter the kind of state propaganda US intelligence says Russia deployed to influence the 2016 presidential election.But former secretary of state Rex Tillerson, who was sacked last week, never accepted the funding and the GEC had continued to focus on online jihadist influence rather than state actors like China and Russia.Analyzing the online profile of suspected jihadists and sympathizers and then “micro-targeting” them for counterpropaganda would be exactly the kind of work that the data-mining firm SCL was set up to do.But the Cambridge Analytica unit, launched in 2013 to offer advanced assistance to election campaign operations, has been accused of using underhand techniques to influence voters in democratic polls.Facebook has suspended the firm’s account for allegedly covertly creating behavioral profiles of 50 million potential US voters as part of its paid support for Trump’s 2016 campaign.Dirty tricksCambridge Analytica denies the claim, but it is also facing a probe from British regulators seeking a court order to seize its servers and investigate allegations of breach of privacy during voter research.And more pressure was piled on the firm when Britain’s Channel 4 news broadcast footage of CA executives boasting to an undercover reporter about alleged election influence techniques.The pair told the reporter, masquerading as a Sri Lankan businessman keen to influence a vote in his home country, that they had secretly worked in African and European countries as well as in the US.They described the practice of sub-contracting dirty tricks work to former British and Israeli intelligence agents and using Ukrainian women to lure unsuspecting candidates into compromising situations.The firm accused Channel 4 of misrepresentation and said the executives had tried to assess the bona fides of a potential client by testing whether he would ask for unethical services they would never provide. © 2018 AFP Explore further The US State Department has a $500,000 contract with the British analysis firm facing allegations it misused Facebook user data and offered to dig dirt on its international clients’ election opponents. Citation: US State Dept has deal with under-fire UK data-miner (2018, March 20) retrieved 18 July 2019 from https://phys.org/news/2018-03-state-dept-under-fire-uk-data-miner.html Cambridge Analytica’s chief executive officer Alexander Nix gives an interview during the Web Summit in Lisbon on November 9, 2017 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Citation: Mideast ride-sharing app Careem says it was hacked (2018, April 23) retrieved 18 July 2019 from https://phys.org/news/2018-04-mideast-ride-sharing-app-careem-hacked.html The Dubai-based competitor to Uber said in a blog post on Monday that it became aware of the hack on Jan. 14 and that it affected “computer systems which hold customer and captain account data.” Careem refers to its drivers as captains.While credit card information remains safe, Careem says that the hackers got access to customers’ name, email addresses, phone numbers and trip data.Careem is one of just a few Gulf startups to be valued at $1 billion. The six-year-old company localized the idea of Uber by also allowing customers to pay by cash.Among its biggest investors is an investment firm chaired by billionaire Saudi Prince Alwaleed bin Talal and the largely state-owned Saudi Telecom Co. Explore further Egypt court suspends ban on Uber and Careem © 2018 The Associated Press. All rights reserved. The Mideast ride-sharing app Careem says it has been hacked. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.